In the production of semiconductor devices, it is necessary that the devices be adequately protected during handling and transporting of the finished parts in order to avoid mechanical damage to the lead tips, the lead finishes, or the assembled packages. The need for protection extends to avoiding damage from static charges or from corrosive environments. Further, the devices must be transported in carriers which are compatible with the customer's in-house manufacturing equipment.
For customers requiring large numbers of identical electronic components, the finished devices 101 are frequently handled in elongated strips of sealed embossed tape 103 having a series of recesses 102 or pockets, as illustrated in FIG. 1. Such a carrier tape 103 normally comprises a flexible plastic material having pockets 102 sized to accommodate correspondingly sized devices 101, with one device being placed in each pocket. The pockets are arranged along the length of the tape 103, and for smaller devices adjacent pockets are positioned across the tape width. The tape edges include perforations for utilization in indexing machines. A cover tape 104 adhered to the horizontal top edges of the carrier tape secures the devices in the pockets.
Typically, at the electronic components manufacturing site the inline process includes removing an empty carrier tape 103 from a reel 105, inserting a semiconductor device 101 in each pocket, sealing the cover tape 104 along the edges of the carrier tape, and rewinding the loaded tape onto a second reel (not shown). At the customer's site, a section of the tape is unwound, the tape covering the devices to be assembled onto a printed circuit board or other interconnection circuitry is removed, and the components are removed from the pockets for final assembly or for testing.
IC devices such as SOIC (small outline IC), TSSOP (thin small outline), SSOP (very small outline) and QFP (quad flat package) include gull wing shaped metal leads spaced in close proximity to each other. The leads, frequently of a copper alloy, are fragile and must be protected from surface damage or deformation. Damaged leads hinder the next process step, such as testing or soldering the device onto a printed circuit board.
As illustrated in FIG. 2a, a carrier tape typically utilizes a pedestal 206 to support the device 201 in the pocket 202. The body of the device rests on the pedestal 206 and is held vertically by the cover tape 209. Other carrier tapes 213, as shown in FIG. 2b, confine the body of the semiconductor component 211 by use of ridges 216 that nest under the shaped leads 218 and next to the body such that the free ends of the leads 211 are spaced away from and ideally do not engage the sidewalls of the pocket 212. The component 211 is centered in the pocket 212 by this design. A cover tape 219 completes the assembly.
However, upon impact from intentional drop testing or from unintentional mishandling, either tape design is inadequate. The component may escape the supporting features and collide with the vertical sidewalls of the pocket. The impact results in damaged leads. If fact, ridges within the pocket may contribute to bending of the leads because as the device is dislodged a lead may be caught straddling a ridge and become damaged.
Therefore, a need exists in the industry for methods to protect electronic components shipped in carrier tapes from damage to the leads and rendering them useless after completing costly fabrication.